WO1994002889A1

WO1994002889A1 - Storage unit

Info

Publication number: WO1994002889A1
Application number: PCT/EP1993/001865
Authority: WO
Inventors: Norbert Katzenschwanz
Original assignee: Lista Neuburg Gmbh + Co.
Priority date: 1992-07-16
Filing date: 1993-07-15
Publication date: 1994-02-03
Also published as: DE9209568U1

Abstract

In order to permit simple and precise positioning of mobile goods-carrying elements (2) in a storage unit (1), in particular a pater noster unit, the invention proposes that an incremental generator (9) is fitted to the drive mechanism (5, 7, 8) for the goods-carrying elements (2) and connected to a counter (10) which is connected both to the selector (11) and to the drive motor (7) to output a stop signal which positions the goods-carrying elements at the input/output opening (6).

Description

Description of storage rack

The invention relates to a storage rack with a plurality of storage goods carrying units, which are conveyed by means of a drive device with a drive motor to at least one storage goods input / output opening and are positioned there for loading / unloading, at least one sensor for positioning the on a selection device selected support unit is provided at the input / output opening by emitting a stop signal to the drive motor.

Storage racks of this type are used in the design of the circulation racks in the horizontal or vertical direction of rotation (so-called paternoster storage), in particular for the storage and order picking of small parts, since this type of storage enables rapid access to a large number of stored parts. The particular advantage is that the stored goods are conveyed to the discharge opening by the drive device and the conveyor chain, so that the removal position remains the same at a convenient handle height. For this purpose, the known shelves or support units for positioning at the removal opening are controlled by a plurality of proximity switches in known circulation racks, which also initiate the braking of the movement into the target position at the removal opening.

With this control using proximity switches or proximity sensors, it is disadvantageous that the proximity sensors respond with relatively low accuracy, have a relatively large scattering angle and also have a hysteresis, depending on whether the conveying direction is counterclockwise or clockwise, for example in a vertical direction Circulation rack the movement of the support units from top to bottom or vice versa. It is also disadvantageous that by installing differently positioned shelves on the support units, as is necessary in adapting to smaller storage items, the number of the required proximity sensors increases sharply. As a result, when relatively low drawers are used, for example as a medication shelf, the construction effort and, in particular, the circuit effort are becoming more and more complicated. In addition, the relatively imprecise positioning with proximity switches is disadvantageous, particularly when using removal robots or automated removal devices, since such handling devices require a very exact and constant removal or placement position compared to manual removal.

From DE-A-25 42 226 a rack system with a counter for positioning the storage container is known. Instead of wearing commutators with sliding contacts, a contactless encoder is used, the signals of which are applied to the input of the counter. The markings are assigned to each individual storage item carrier. A single reference marking is also provided, which resets the counter for correction and "calibration". However, since the contactless encoder is arranged on the storage goods containers, the positioning accuracy suffers because chain elongations can falsify the measurement. A high number of markings is also required.

From DE-A-35 12 513 and DE-A-35 12 359 is generally a control system for interlinked machine tools such. B. forming presses and an incremental encoder on an auxiliary shaft for a feed drive in machine tools are known.

DD-A-261 663 and DE-A-17 73 460 generally describe displacement measurement for measuring machines or machine tools.

US-A-3,738,475 describes a conveyor system with a digital controller for synchronizing the input / output stations. The position is measured using a perforated disk as a replacement for proximity switches, see above that their frequent "running over" is prevented. However, this is not a storage rack. In addition, only one is certified. position repeatedly approached.

In VDI Report No. 151, 1969, p. 31, digital incremental position controls for shelf-mounted conveyors are described, which are arranged at the individual storage positions in a star shelf or the removal vehicle. Thus, there is no reference to storage racks with movable support units.

Accordingly, the invention is based on the object of specifying a storage rack, in particular a circulating rack, which enables a simpler and more precise positioning of the carrying units on the storage goods input / output.

This object is achieved by a storage rack according to the features of claim 1.

By using an incremental encoder and an associated counter, counting pulses are available in very close succession as control signals, so that a very high resolution and thus a reproducible positioning accuracy of less than one millimeter is achieved. By defining the subject levels of the support units as a certain sum of counting pulses, any division of the subject levels is possible. For example, a simple division of software can be used to define a three-way division of the supporting units. This is also possible, for example, in the teach-in process, in which the reference levels are assigned to the corresponding number of counting pulses. Any stop position that deviates from the normal position can also be defined, in particular for the use of removal devices, in order to enable the removal device to be accessed more cheaply. In addition, different holding positions are possible on each support unit due to the precise resolution, so that in the case of different support floors arranged next to one another, divisions depending on whether on the right, middle or left area of the support unit to be accessed, different breakpoints possible. It should be noted that this can be quickly and easily assigned and changed again by simple software changes.

In addition, the high resolution due to the incremental encoder with the associated counter in the millimeter range advantageously achieves a gentle braking of the conveying movement, for example by switching off the drive motor twenty counting pulses before the selected stop position and initiating the braking operation. Due to the high resolution of the incremental encoder and the digital counter, an exact braking ramp is possible until the circulating conveyor or the storage goods support units of the dynamic storage rack stop. In this case, an evaluation of the counting pulses is also possible during the bre sens, so that an exact braking of the conveying or circulating movement can take place by constant comparison of the actual setpoint. This is particularly important in the case of unevenly loaded revolving shelves, since it is not always possible to reliably avoid driving past the target position due to the greatly varying inertia forces in the known revolving shelf controls.

Further advantageous embodiments are the subject of the dependent claims.

An exemplary embodiment shown in the drawing is explained and described in more detail below. 1 shows a schematic representation of a circulating rack and the control and counting device according to the innovation.

A storage rack 1 in the form of a circulation rack (paternoster cabinet) has a large number of support units 2 which are identified by capital letters and which are designed here in a box-like manner for accommodating stored goods. However, flat shelves can also be used to insert Container boxes or drawers may be provided. The support units 2 are connected via unsupported support levers to the conveyor chain 3 and, in addition, during their Umla movement freely oscillating or guided in a guide path, not shown.

The carrying or conveyor chain 3 runs over an upper deflection wheel 4 and a lower drive wheel 5. Depending on the width dimension of the storage rack 1, at least one further conveyor chain 3 is provided in a corresponding manner.

Due to the rotating movement of the conveyor chain 3, the support units 2 are guided past an input / output opening 6, so that stored goods can be removed from the support units 2 or can also be stored. As is generally customary, the input / output opening 6 is at the operator's hand height, so that here, for example, the carrying units E and F can be accessed.

The drive wheel 5 for the conveyor chain 3 is driven by a drive motor 7 via a drive chain 8 and an intermediate gear 12, an incremental encoder 9 is provided above the drive wheel 5 in the space between the two runs of the conveyor chain 3, which scans the drive wheel 5 and accordingly the teeth arranged on the circumference and passing the incremental encoder 9 on the drive wheel 5 generate a rectangular signal or a similar pulse shape. A Hall sensor is preferably used as the incremental encoder 9, but other magnetic or optical sensors, such as light barriers, can also be used. These measuring pulses are fed to a counter 10 (digital counter module), which digitally detects the counting pulses and, upon reaching a predetermined stop position by a selection device 11 via the input / output opening 6, via appropriate control components known per se, such as relays, a stop signal to the Drive motor 7 outputs. The counter 10 further comprises a memory 13 and a control computer 14 and is preferably designed as a microprocessor or integrated circuit.

It is essential here that the individual holding positions of the carrying units 2 are predetermined by the incremental encoder 9 by a certain number of counting pulses, a zero or reference point being defined for the initial initiation. This can be done by a single proximity sensor, for example on the support unit A. However, the reference point can be defined on any support unit 2. It is assumed here that the lower edge of the support unit F forms the reference point. Assuming that each support unit 2 is three hundred millimeters high and the resolution of the incremental encoder 9 z. B. is a millimeter, 300 counts are registered accordingly in the further movement of a support unit 2. If, therefore, the support unit H is to be moved to the input / output opening 6, that is to be conveyed by two support units, six hundred counting pulses are emitted by the incremental encoder 9 and reached in the counter 10 until the stop position is reached, so that after reaching exactly this number of six hundred counts of the drive motor 7 is switched off. For a safe and gentle stopping during the orbital movement can z. B. the counting No. 580 or 590 already braking the circular movement z. B. initiated by reducing the speed of the drive motor 7.

As shown on the data line between the incremental encoder 9 and the counter 10, the pulse train preferably has a rectangular shape, the incremental encoder 9 preferably having two counter channels 9a and 9b offset from one another by 90 °, so that the rising edge of the measuring pulse occurs in one direction of rotation is offset by 90 ", while in the opposite direction of rotation the edges of the measuring pulses are offset by 270 °. This offset, which must not be 180 °, can be used to differentiate between Which direction of rotation the storage rack 1 is operated, since such circulation conveyors usually allow both directions of rotation in order to get to the desired support unit 2 by the shortest route. If, for example, the support unit A is selected starting from the position shown, the circulation conveyor is operated counterclockwise, since only the distance F to A has to be covered.

The resolution of the digital counting device depends crucially on the subdivision of the rotating parts interacting with the incremental encoder 9. If, for example, the teeth on the drive wheel 5 are roughly divided, the desired resolution of 1 mm can hardly be achieved; instead, a separate measuring disk in the form of a finely divided toothed wheel can be provided parallel to the drive wheel 5. However, the incremental encoder 9 can also be provided on the drive motor 7 rotating at a higher speed or on the gear 12, as indicated by the positions 9 ′ ″ and 9 ″ in dashed lines. A further arrangement is indicated with the reference symbol 9 ', the incremental encoder 9 scanning the drive chain 8 passing by and thereby generating the desired signal shape. For example, the chain pins of the drive chain 8 can also be extended, so that a digital signal is obtained which is then used for incremental counting in the counter 10. However, the removal position is preferably arranged on parts which are not subject to wear, for example directly on the drive shaft of the drive motor 7, so that chain elongations do not influence the measurement result. In addition, by attaching a measuring disc in the form of a toothed wheel to the drive motor 7, the mechanical chain elongation can be compensated for by software correction, for example, with a chain elongation of 0.3% at the above-mentioned resolution with three hundred counts per carrier unit, the distance between the carrier units a count is changed. The digital counting device described above can be used both on vertically rotating and on horizontally rotating shelf storage facilities. It is essential here that the individual breakpoints for the support units 2 can be defined by simple software changes. According to the above example of 300 counts per carrier unit, the stopping point for the carrier unit is B = 300, for C = 600, for D = 900 pulses, etc., when carrier unit A forms the reference point. Should now z. B. the support unit D can be divided in the middle by an intermediate floor, the stop position of this intermediate floor can be determined at 750 counts by simple software input. With two, evenly arranged shelves, the stop positions would be 700 and 800 counts, so that changes to the circulation rack can be made quickly without additional installations of switches etc.

Likewise, the counting device described above can be used as a special form of dynamic storage racks for sliding racks, i. H. those with movable storage goods support units are used, the storage goods input / output point being reached by opening a storage aisle in the shelf block, which corresponds to the input / output opening of a circulating rack.

Claims

Claims:

1. Storage rack with a plurality of stored goods carrying units, which are conveyed by means of a drive device with a drive motor to at least one stored goods input / output opening and are positioned there for loading / unloading, at least one measuring sensor for positioning the carrying unit selected on a selection device is provided at the input / output opening by emitting a stop signal to the drive motor, characterized in that the sensor is an incremental encoder (9) which is arranged on the drive device (5, 7, 8) and is connected to a counter (10) which is connected on the one hand to the selection device (11) and on the other hand to the drive motor (7) for emitting the stop signal for positioning at the input / output opening (6).

2. Storage rack according to claim 1, characterized in that the incremental encoder (9) has two mutually offset counting channels (9a, 9b).

3. Storage rack according to claim 2, characterized in that the counting channels (9a, 9b) are offset by 90 "to each other.

4. Storage rack according to one of claims 1 to 3, characterized in that the stop signal to the drive motor (7) is emitted by a predetermined number of pulses before the selected stop position.

5. Storage rack according to one of claims 1 to 4, characterized in that the incremental encoder (9) on the drive motor (7) or the associated gear (12) is arranged.

6. Storage rack according to one of claims 1 to 4, characterized in that the incremental encoder (9) on a drive motor (7) outgoing drive chain (8) is arranged.

7. Storage rack according to one of claims 1 to 4, characterized in that the incremental encoder (9) on a drive wheel (5) of a conveyor chain (3) is arranged on which the support units (2) are attached.

8. Storage rack according to one of claims 1 to 7, characterized in that the counter (10) has a memory (13) for storing the respective holding positions of the support units (2).

9. Storage rack according to one of claims 1 to 8, characterized in that the incremental encoder (9) is assigned a serrated measuring disc which is attached to a rotating part of the drive device (5, 7, 8).

10. Storage rack according to claim 8, characterized in that the counter (10) and the memory (13) are arranged on an integrated circuit.